The invention relates generally to high frequency impedance measurements such as the use of reflectometry for antenna measurements. More particularly, the invention relates to reflectometry techniques utilizing noise modulation to reduce the effects of interfering signals.
Antenna impedance measurement is commonly performed by measurement of the voltage standing wave ratio (VSWR). Measurement of the VSWR, however, is more complicated when the antenna under test is in the presence of strong interfering signals. Such interfering signals can occur, for example, from nearby antennas or other transmission devices in the area of the antenna under test.
The objectives exist, therefore, for providing apparatus and methods for measuring VSWR even in the presence of strong interfering signals at the antenna or antenna test port.